# Copyright 2018 The TensorFlow Authors. All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
# ==============================================================================
"""Part of the Keras training engine related to Python generators of array data.
"""

import functools
import math

import numpy as np
import tensorflow.compat.v2 as tf

from keras import backend
from keras import callbacks as cbks
from keras.engine import training_utils
from keras.engine import training_utils_v1
from keras.utils import data_utils
from keras.utils import generic_utils
from keras.utils.mode_keys import ModeKeys

# isort: off
from tensorflow.python.platform import tf_logging as logging


def model_iteration(
    model,
    data,
    steps_per_epoch=None,
    epochs=1,
    verbose=1,
    callbacks=None,
    validation_data=None,
    validation_steps=None,
    validation_freq=1,
    class_weight=None,
    max_queue_size=10,
    workers=1,
    use_multiprocessing=False,
    shuffle=False,
    initial_epoch=0,
    mode=ModeKeys.TRAIN,
    batch_size=None,
    steps_name="steps",
    **kwargs
):
    """Loop function for arrays of data with modes TRAIN/TEST/PREDICT.

    Args:
        model: Keras Model instance.
        data: Either a tuple of NumPy/Tensor inputs (i.e. `(x,)` or `(x, y)` or
          `(x, y, sample_weights)`) or a generator or
          `keras.utils.data_utils.Sequence` object or Eager Iterator or Dataset.
        steps_per_epoch: Total number of steps (batches of samples) before
          declaring one epoch finished and starting the next epoch. Ignored with
          the default value of `None`.
        epochs: Number of times to iterate over the data.
        verbose: 0, 1, or 2. Verbosity mode.
          0 = silent, 1 = progress bar, 2 = one line per epoch.
          Note that the progress bar is not particularly useful when
          logged to a file, so verbose=2 is recommended when not running
          interactively (eg, in a production environment).
        callbacks: List of callbacks to be called during training.
        validation_data: Either a tuple of NumPy/Tensor inputs (i.e. `(x,)` or
          `(x, y)` or `(x, y, sample_weights)`) or a generator or
          `keras.utils.data_utils.Sequence` object or Eager Iterator or Dataset.
        validation_steps: Total number of steps (batches of samples) before
          declaring validation finished.
        validation_freq: Only relevant if validation data is provided. Integer
          or `collections.abc.Container` instance (e.g. list, tuple, etc.). If
          an integer, specifies how many training epochs to run before a new
          validation run is performed, e.g. `validation_freq=2` runs validation
          every 2 epochs. If a Container, specifies the epochs on which to run
          validation, e.g. `validation_freq=[1, 2, 10]` runs validation at the
          end of the 1st, 2nd, and 10th epochs.
        class_weight: Dictionary mapping class indices to a weight for the
            class.
        max_queue_size: Integer. Maximum size for the generator queue. If
          unspecified, `max_queue_size` will default to 10.
        workers: Integer. Maximum number of processes to spin up when using
          process-based threading. If unspecified, `workers` will default to 1.
          If 0, will execute the generator on the main thread.
        use_multiprocessing: Boolean. If `True`, use process-based threading. If
          unspecified, `use_multiprocessing` will default to `False`. Note that
          because this implementation relies on multiprocessing, you should not
          pass non-picklable arguments to the generator as they can't be passed
          easily to children processes.
        shuffle: Boolean. Whether to shuffle the order of the batches at the
          beginning of each epoch. Only used with instances of `Sequence`
          (`keras.utils.Sequence`). Has no effect when `steps_per_epoch` is not
          `None`.
        initial_epoch: Epoch at which to start training (useful for resuming a
          previous training run).
        mode: One of ModeKeys.TRAIN/ModeKeys.TEST/ModeKeys.PREDICT.
        batch_size: Integer batch size or None if unknown. Will only be used if
          `data` is in NumPy/Tensor format.
        steps_name: The string name of the steps argument, either `steps`,
          `validation_steps`, or `steps_per_epoch`. Only used for error message
          formatting.
        **kwargs: Additional arguments for backwards compatibility. `steps` is
          accepted as an alias for `steps_per_epoch`.

    Returns:
        - In TRAIN mode: `History` object.
        - In TEST mode: Evaluation metrics.
        - In PREDICT mode: Outputs of the Model called on inputs.

    Raises:
        ValueError: in case of invalid arguments.
    """
    if "steps" in kwargs:
        steps_per_epoch = kwargs["steps"]

    # Determine the number of steps per epoch and whether we should reset the
    # dataset at the end of each epoch.
    reset_dataset_after_each_epoch = False
    original_dataset = None
    is_dataset = isinstance(data, (tf.data.Dataset, tf.compat.v1.data.Dataset))
    if is_dataset:
        original_dataset = data
        if steps_per_epoch is None:
            reset_dataset_after_each_epoch = True
            steps_per_epoch = training_utils_v1.infer_steps_for_dataset(
                model,
                data,
                steps_per_epoch,
                epochs=epochs,
                steps_name=steps_name,
            )

    # Convert to a format that supports `next(generator)`.
    generator, steps_per_epoch = convert_to_generator_like(
        data,
        steps_per_epoch=steps_per_epoch,
        batch_size=batch_size,
        epochs=epochs - initial_epoch,
        shuffle=shuffle,
    )

    do_validation = validation_data is not None
    is_sequence = isinstance(generator, data_utils.Sequence)
    _validate_arguments(
        is_sequence,
        is_dataset,
        use_multiprocessing,
        workers,
        steps_per_epoch,
        validation_data,
        validation_steps,
        mode,
        kwargs,
    )

    batch_function = _make_execution_function(
        model, mode, class_weight=class_weight
    )

    # Create the queue for the generator.
    enqueuer = None
    if not is_dataset:
        generator, enqueuer = _make_enqueued_generator(
            generator,
            workers=workers,
            use_multiprocessing=use_multiprocessing,
            max_queue_size=max_queue_size,
            shuffle=shuffle,
        )

    num_samples_or_steps, use_steps = _get_num_samples_or_steps(
        data, steps_per_epoch
    )

    count_mode = "steps" if use_steps else "samples"
    callbacks = cbks.configure_callbacks(
        callbacks,
        model,
        do_validation=do_validation,
        epochs=epochs,
        steps_per_epoch=steps_per_epoch,
        batch_size=batch_size,
        samples=num_samples_or_steps,
        count_mode=count_mode,
        verbose=verbose,
        mode=mode,
    )

    if mode == ModeKeys.PREDICT:
        aggregator = training_utils_v1.OutputsAggregator(
            True, steps=steps_per_epoch
        )
    else:
        aggregator = training_utils_v1.MetricsAggregator(
            True, steps=steps_per_epoch
        )

    should_set_learning_phase = tf.executing_eagerly() and model.run_eagerly
    if should_set_learning_phase:
        learning_phase_scope = backend.eager_learning_phase_scope(
            1 if mode == ModeKeys.TRAIN else 0
        )
        learning_phase_scope.__enter__()

    callbacks.model.stop_training = False
    callbacks._call_begin_hook(mode)

    initial_epoch = model._maybe_load_initial_epoch_from_ckpt(
        initial_epoch, mode
    )

    for epoch in range(initial_epoch, epochs):
        if callbacks.model.stop_training:
            break

        # Setup work for each epoch.
        model.reset_metrics()
        epoch_logs = {}
        if mode == ModeKeys.TRAIN:
            callbacks.on_epoch_begin(epoch, epoch_logs)

        if steps_per_epoch is None:
            # Loop over dataset until `OutOfRangeError` is raised.
            target_steps = np.inf
        else:
            # Loop over dataset for the specified number of steps.
            target_steps = steps_per_epoch

        step = 0
        while step < target_steps:
            batch_data = _get_next_batch(generator)
            if batch_data is None:
                if is_dataset:
                    # The dataset passed by the user ran out of batches.  Now we
                    # know the cardinality of the dataset.  If steps_per_epoch
                    # was specified, then running out of data is unexpected, so
                    # we stop training and inform the user.
                    if steps_per_epoch:
                        callbacks.model.stop_training = True
                        logging.warning(
                            "Your dataset ran out of data; interrupting "
                            "training. Make sure that your dataset can "
                            "generate at least `%s * epochs` batches (in "
                            "this case, %d batches). You may need to use "
                            "the repeat() function when building your dataset."
                            % (steps_name, steps_per_epoch * epochs)
                        )
                    elif step > 0:
                        steps_per_epoch = step
                        aggregator.steps = steps_per_epoch
                else:
                    # We ran out of batches while the user passed an iterator
                    # (legacy).
                    callbacks.model.stop_training = True
                    logging.warning(
                        "Your dataset iterator ran out of data; "
                        "interrupting training. Make sure that your iterator "
                        "can generate at least `%s * epochs` "
                        "batches (in this case, %d batches). You may need to"
                        "use the repeat() function when building your "
                        "dataset." % (steps_name, steps_per_epoch * epochs)
                    )
                break

            # `batch_size` used for validation data if validation
            # data is NumPy/EagerTensors.
            batch_size = int(tf.nest.flatten(batch_data)[0].shape[0])

            # Callbacks batch begin.
            batch_logs = {"batch": step, "size": batch_size}
            callbacks._call_batch_hook(mode, "begin", step, batch_logs)

            is_deferred = not model._is_compiled
            batch_outs = batch_function(*batch_data)
            if not isinstance(batch_outs, list):
                batch_outs = [batch_outs]

            if step == 0:
                aggregator.create(batch_outs)

                if is_deferred:
                    # Set callbacks params. We do this here when model is
                    # compiled only in the first iteration of this loop
                    # (deferred build scenario).
                    cbks.set_callback_parameters(
                        callbacks,
                        model,
                        do_validation=do_validation,
                        batch_size=batch_size,
                        epochs=epochs,
                        steps_per_epoch=steps_per_epoch,
                        samples=num_samples_or_steps,
                        verbose=verbose,
                        mode=mode,
                    )

            # Aggregate results.
            aggregator.aggregate(batch_outs)

            # Callbacks batch end.
            batch_logs = callbacks.make_logs(
                model, batch_logs, batch_outs, mode
            )
            callbacks._call_batch_hook(mode, "end", step, batch_logs)
            step += 1

            if callbacks.model.stop_training:
                break

        aggregator.finalize()
        results = aggregator.results
        epoch_logs = callbacks.make_logs(model, epoch_logs, results, mode)
        if len(results) == 1:
            results = results[0]

        # Run the test loop every epoch during training.
        if (
            do_validation
            and training_utils_v1.should_run_validation(validation_freq, epoch)
            and not callbacks.model.stop_training
        ):
            val_results = model_iteration(
                model,
                validation_data,
                steps_per_epoch=validation_steps,
                batch_size=batch_size,
                class_weight=class_weight,
                workers=workers,
                use_multiprocessing=use_multiprocessing,
                max_queue_size=max_queue_size,
                callbacks=callbacks,
                verbose=verbose,
                mode=ModeKeys.TEST,
                steps_name="validation_steps",
            )

            if not isinstance(val_results, list):
                val_results = [val_results]
            epoch_logs = callbacks.make_logs(
                model, epoch_logs, val_results, mode, prefix="val_"
            )

        if mode == ModeKeys.TRAIN:
            # Epochs only apply to `fit`.
            callbacks.on_epoch_end(epoch, epoch_logs)

        # Recreate dataset iterator for the next epoch.
        if reset_dataset_after_each_epoch and epoch < epochs - 1:
            generator = tf.compat.v1.data.make_one_shot_iterator(
                original_dataset
            )

    model._successful_loop_finish = True
    callbacks._call_end_hook(mode)

    if enqueuer is not None:
        enqueuer.stop()

    if should_set_learning_phase:
        learning_phase_scope.__exit__(None, None, None)

    if mode == ModeKeys.TRAIN:
        return model.history
    return results


# Maintain compatibility with the existing names.
fit_generator = functools.partial(model_iteration, mode=ModeKeys.TRAIN)
evaluate_generator = functools.partial(
    model_iteration, mode=ModeKeys.TEST, shuffle=False
)
predict_generator = functools.partial(
    model_iteration, mode=ModeKeys.PREDICT, shuffle=False
)


def _get_next_batch(generator):
    """Retrieves the next batch of input data."""
    try:
        generator_output = next(generator)
    except (StopIteration, tf.errors.OutOfRangeError):
        return None

    if not isinstance(generator_output, tuple):
        # Always wrap in a tuple.
        generator_output = (generator_output,)
    if len(generator_output) not in [1, 2, 3]:
        raise ValueError(
            "Output of generator should be a tuple of 1 or 2 or 3 "
            "elements: (input,) or (input, target) or "
            "(input, target, sample_weights). Received {}".format(
                generator_output
            )
        )
    return generator_output


def _validate_arguments(
    is_sequence,
    is_dataset,
    use_multiprocessing,
    workers,
    steps_per_epoch,
    validation_data,
    validation_steps,
    mode,
    kwargs,
):
    """Raises errors if arguments are invalid.

    Args:
      is_sequence: Boolean, whether data is a `keras.utils.data_utils.Sequence`
        instance.
      is_dataset: Boolean, whether data is a dataset instance.
      use_multiprocessing: Boolean. If `True`, use process-based threading. If
        unspecified, `use_multiprocessing` will default to `False`. Note that
        because this implementation relies on multiprocessing, you should not
        pass non-picklable arguments to the generator as they can't be passed
        easily to children processes.
      workers: Integer. Maximum number of processes to spin up when using
        process-based threading. If unspecified, `workers` will default to 1. If
        0, will execute the generator on the main thread.
      steps_per_epoch: Total number of steps (batches of samples) before
        declaring one epoch finished and starting the next epoch. Ignored with
        the default value of `None`.
      validation_data: Either a tuple of NumPy/Tensor inputs (i.e. `(x,)` or
        `(x, y)` or `(x, y, sample_weights)`) or a generator or
        `keras.utils.data_utils.Sequence` object or Eager Iterator or Dataset.
      validation_steps: Total number of steps (batches of samples) before
        declaring validation finished.
      mode: One of ModeKeys.TRAIN/ModeKeys.TEST/ModeKeys.PREDICT.
      kwargs: Additional arguments for backwards compatibility.

    Raises:
      ValueError: If `steps_per_epoch` or `validation_steps` are not passed
        for data types that require them, or if unrecognized keyword
        arguments are passed.
    """
    if not is_sequence and use_multiprocessing and workers > 1:
        logging.warning(
            UserWarning(
                "Using a generator with `use_multiprocessing=True`"
                " and multiple workers may duplicate your data."
                " Please consider using the `keras.utils.Sequence`"
                " class."
            )
        )

    if steps_per_epoch is None and not is_dataset:
        arg_name = "steps_per_epoch" if mode == ModeKeys.TRAIN else "steps"
        raise ValueError(
            "Please specify the number of steps via the "
            "`{}` argument.".format(arg_name)
        )

    val_gen = data_utils.is_generator_or_sequence(
        validation_data
    ) or isinstance(validation_data, tf.data.Iterator)
    if (
        val_gen
        and not isinstance(validation_data, data_utils.Sequence)
        and not validation_steps
    ):
        raise ValueError("Please specify the `validation_steps` argument.")

    if any(k != "steps" for k in kwargs):
        raise ValueError(
            "Invalid arguments passed: {}".format(
                [k for k in kwargs if k != "steps"]
            )
        )


def convert_to_generator_like(
    data, batch_size=None, steps_per_epoch=None, epochs=1, shuffle=False
):
    """Make a generator out of NumPy or EagerTensor inputs.

    Args:
      data: Either a generator or `keras.utils.data_utils.Sequence` object or
        `Dataset`, `Iterator`, or a {1,2,3}-tuple of NumPy arrays or
        EagerTensors.  If a tuple, the elements represent `(x, y,
        sample_weights)` and may be `None` or `[None]`.
      batch_size: Used when creating a generator out of tuples of NumPy arrays
        or EagerTensors.
      steps_per_epoch: Steps of the generator to run each epoch. If `None` the
        number of steps will be read from the data (for
        `keras.utils.data_utils.Sequence` types).
      epochs: Total number of epochs to run.
      shuffle: Whether the data should be shuffled.

    Returns:
      - Generator, `keras.utils.data_utils.Sequence`, or `Iterator`.

    Raises:
      - ValueError: If `batch_size` is not provided for NumPy or EagerTensor
        inputs.
    """
    if isinstance(data, tuple):
        # Scrub `Nones` that might have been passed for `targets`,
        # `sample_weights`.
        data = tuple(
            ele
            for ele in data
            if not all(e is None for e in tf.nest.flatten(ele))
        )

    if data_utils.is_generator_or_sequence(data) or isinstance(
        data, tf.data.Iterator
    ):
        if isinstance(data, data_utils.Sequence):
            if steps_per_epoch is None:
                steps_per_epoch = len(data)
        return data, steps_per_epoch
    if isinstance(data, tf.data.Dataset):
        return tf.compat.v1.data.make_one_shot_iterator(data), steps_per_epoch

    # Create generator from NumPy or EagerTensor Input.
    num_samples = int(tf.nest.flatten(data)[0].shape[0])
    if batch_size is None:
        raise ValueError(
            "When passing input data as arrays, do not specify "
            "`steps_per_epoch`/`steps` argument. "
            "Please use `batch_size` instead."
        )
    steps_per_epoch = int(math.ceil(num_samples / batch_size))

    def _gen(data):
        """Makes a generator out of a structure of NumPy/EagerTensors."""
        index_array = np.arange(num_samples)
        for _ in range(epochs):
            if shuffle:
                np.random.shuffle(index_array)
            batches = generic_utils.make_batches(num_samples, batch_size)
            for (batch_start, batch_end) in batches:
                batch_ids = index_array[batch_start:batch_end]
                flat_batch_data = training_utils.slice_arrays(
                    tf.nest.flatten(data), batch_ids, contiguous=(not shuffle)
                )
                yield tf.nest.pack_sequence_as(data, flat_batch_data)

    return _gen(data), steps_per_epoch


def _make_enqueued_generator(
    generator,
    workers=1,
    use_multiprocessing=False,
    max_queue_size=10,
    shuffle=False,
):
    """Create a buffered queue of next elements of the generator."""
    is_sequence = isinstance(generator, data_utils.Sequence)
    enqueuer = None
    if workers > 0:
        if is_sequence:
            enqueuer = data_utils.OrderedEnqueuer(
                generator,
                use_multiprocessing=use_multiprocessing,
                shuffle=shuffle,
            )
        else:
            enqueuer = data_utils.GeneratorEnqueuer(
                generator, use_multiprocessing=use_multiprocessing
            )
        enqueuer.start(workers=workers, max_queue_size=max_queue_size)
        output_generator = enqueuer.get()
    else:
        if is_sequence:
            output_generator = data_utils.iter_sequence_infinite(generator)
        else:
            output_generator = generator
    return output_generator, enqueuer


def _make_execution_function(model, mode, class_weight=None):
    """Makes function to run one step of model execution."""
    if mode == ModeKeys.TRAIN:
        f = functools.partial(model.train_on_batch, class_weight=class_weight)
    elif mode == ModeKeys.TEST:
        f = model.test_on_batch
    else:
        # Match signature of other modes to allow
        # 1, 2, or 3-tuples from generator
        def predict_on_batch(x, y=None, sample_weights=None):
            return model.predict_on_batch(x)

        f = predict_on_batch

    # Maintain stateful metrics across batch-level calls.
    if mode != ModeKeys.PREDICT:
        f = functools.partial(f, reset_metrics=False)

    return f


def _get_num_samples_or_steps(data, steps_per_epoch):
    """Returns number of samples or steps, and whether to use steps count
    mode."""
    flat_inputs = tf.nest.flatten(data)
    if hasattr(flat_inputs[0], "shape"):
        return int(flat_inputs[0].shape[0]), False
    return steps_per_epoch, True


class GeneratorOrSequenceTrainingLoop(training_utils_v1.TrainingLoop):
    """Generator-like.

    Input is Python generator, or Sequence object.

    The difference between this class and `GeneratorLikeTrainingFunction` is
    that this class only handles inputs that with x, y and sample_weight fused
    into one param.
    """

    def fit(
        self,
        model,
        x=None,
        y=None,
        batch_size=None,
        epochs=1,
        verbose=1,
        callbacks=None,
        validation_split=0.0,
        validation_data=None,
        shuffle=True,
        class_weight=None,
        sample_weight=None,
        initial_epoch=0,
        steps_per_epoch=None,
        validation_steps=None,
        validation_freq=1,
        max_queue_size=10,
        workers=1,
        use_multiprocessing=False,
    ):
        model._validate_or_infer_batch_size(batch_size, steps_per_epoch, x)
        training_utils_v1.check_generator_arguments(
            y, sample_weight, validation_split=validation_split
        )
        return fit_generator(
            model,
            x,
            steps_per_epoch=steps_per_epoch,
            epochs=epochs,
            verbose=verbose,
            callbacks=callbacks,
            validation_data=validation_data,
            validation_steps=validation_steps,
            validation_freq=validation_freq,
            class_weight=class_weight,
            max_queue_size=max_queue_size,
            workers=workers,
            use_multiprocessing=use_multiprocessing,
            shuffle=shuffle,
            initial_epoch=initial_epoch,
            steps_name="steps_per_epoch",
        )

    def evaluate(
        self,
        model,
        x=None,
        y=None,
        batch_size=None,
        verbose=1,
        sample_weight=None,
        steps=None,
        callbacks=None,
        max_queue_size=10,
        workers=1,
        use_multiprocessing=False,
    ):
        model._validate_or_infer_batch_size(batch_size, steps, x)
        training_utils_v1.check_generator_arguments(y, sample_weight)
        return evaluate_generator(
            model,
            x,
            steps=steps,
            verbose=verbose,
            callbacks=callbacks,
            max_queue_size=max_queue_size,
            workers=workers,
            use_multiprocessing=use_multiprocessing,
        )

    def predict(
        self,
        model,
        x,
        batch_size=None,
        verbose=0,
        steps=None,
        callbacks=None,
        max_queue_size=10,
        workers=1,
        use_multiprocessing=False,
    ):
        model._validate_or_infer_batch_size(batch_size, steps, x)
        return predict_generator(
            model,
            x,
            steps=steps,
            verbose=verbose,
            callbacks=callbacks,
            max_queue_size=max_queue_size,
            workers=workers,
            use_multiprocessing=use_multiprocessing,
        )


class EagerDatasetOrIteratorTrainingLoop(training_utils_v1.TrainingLoop):
    """A non-distributed Dataset or iterator in eager execution."""

    def fit(
        self,
        model,
        x=None,
        y=None,
        batch_size=None,
        epochs=1,
        verbose=1,
        callbacks=None,
        validation_split=0.0,
        validation_data=None,
        shuffle=True,
        class_weight=None,
        sample_weight=None,
        initial_epoch=0,
        steps_per_epoch=None,
        validation_steps=None,
        validation_freq=1,
        **kwargs
    ):
        model._validate_or_infer_batch_size(batch_size, steps_per_epoch, x)
        # Make sure that y, sample_weights, validation_split are not passed.
        training_utils_v1.validate_dataset_input(
            x, y, sample_weight, validation_split
        )
        if (
            isinstance(x, (tf.compat.v1.data.Dataset, tf.data.Dataset))
            and shuffle
        ):
            training_utils_v1.verify_dataset_shuffled(x)

        return fit_generator(
            model,
            x,
            steps_per_epoch=steps_per_epoch,
            epochs=epochs,
            verbose=verbose,
            callbacks=callbacks,
            validation_data=validation_data,
            validation_steps=validation_steps,
            validation_freq=validation_freq,
            class_weight=class_weight,
            workers=0,
            shuffle=shuffle,
            initial_epoch=initial_epoch,
            steps_name="steps_per_epoch",
        )

    def evaluate(
        self,
        model,
        x=None,
        y=None,
        batch_size=None,
        verbose=1,
        sample_weight=None,
        steps=None,
        callbacks=None,
        **kwargs
    ):
        model._validate_or_infer_batch_size(batch_size, steps, x)
        # Make sure that y, sample_weights, validation_split are not passed.
        training_utils_v1.validate_dataset_input(x, y, sample_weight)
        return evaluate_generator(
            model,
            x,
            steps=steps,
            verbose=verbose,
            workers=0,
            callbacks=callbacks,
        )

    def predict(
        self,
        model,
        x,
        batch_size=None,
        verbose=0,
        steps=None,
        callbacks=None,
        **kwargs
    ):
        model._validate_or_infer_batch_size(batch_size, steps, x)
        return predict_generator(
            model,
            x,
            steps=steps,
            verbose=verbose,
            workers=0,
            callbacks=callbacks,
        )


class GeneratorLikeTrainingLoop(training_utils_v1.TrainingLoop):
    """TrainingLoop that handle inputs like python generator.

    This is the default handler for most of the input data types, includes
    symbolic tensors or Numpy array-like, Datasets and iterators in graph mode
    (since they generate symbolic tensors). This Function is used to handle
    model with `run_eagerly` = True.
    """

    def fit(
        self,
        model,
        x=None,
        y=None,
        batch_size=None,
        epochs=1,
        verbose=1,
        callbacks=None,
        validation_split=0.0,
        validation_data=None,
        shuffle=True,
        class_weight=None,
        sample_weight=None,
        initial_epoch=0,
        steps_per_epoch=None,
        validation_steps=None,
        validation_freq=1,
        **kwargs
    ):
        batch_size = model._validate_or_infer_batch_size(
            batch_size, steps_per_epoch, x
        )
        x, y, sample_weights = model._standardize_user_data(
            x,
            y,
            sample_weight=sample_weight,
            class_weight=class_weight,
            batch_size=batch_size,
            check_steps=True,
            steps_name="steps_per_epoch",
            steps=steps_per_epoch,
            validation_split=validation_split,
            shuffle=shuffle,
        )

        if validation_data:
            validation_data = model._prepare_validation_data(
                validation_data, batch_size, validation_steps
            )
        elif validation_split and 0.0 < validation_split < 1.0:
            (
                x,
                y,
                sample_weights,
                val_x,
                val_y,
                val_sample_weights,
            ) = training_utils_v1.split_training_and_validation_data(
                x, y, sample_weights, validation_split
            )
            validation_data = (val_x, val_y, val_sample_weights)
        else:
            if validation_steps:
                raise ValueError(
                    "`validation_steps` should not be specified if "
                    "`validation_data` is None."
                )

        return fit_generator(
            model,
            (x, y, sample_weights),
            steps_per_epoch=steps_per_epoch,
            batch_size=batch_size,
            epochs=epochs,
            verbose=verbose,
            callbacks=callbacks,
            validation_data=validation_data,
            validation_steps=validation_steps,
            validation_freq=validation_freq,
            workers=0,
            shuffle=shuffle,
            initial_epoch=initial_epoch,
            steps_name="steps_per_epoch",
        )

    def evaluate(
        self,
        model,
        x=None,
        y=None,
        batch_size=None,
        verbose=1,
        sample_weight=None,
        steps=None,
        callbacks=None,
        **kwargs
    ):
        batch_size = model._validate_or_infer_batch_size(batch_size, steps, x)
        x, y, sample_weights = model._standardize_user_data(
            x,
            y,
            sample_weight=sample_weight,
            batch_size=batch_size,
            check_steps=True,
            steps_name="steps",
            steps=steps,
        )
        return evaluate_generator(
            model,
            (x, y, sample_weights),
            steps=steps,
            batch_size=batch_size,
            verbose=verbose,
            workers=0,
            callbacks=callbacks,
        )

    def predict(
        self,
        model,
        x,
        batch_size=None,
        verbose=0,
        steps=None,
        callbacks=None,
        **kwargs
    ):
        batch_size = model._validate_or_infer_batch_size(batch_size, steps, x)
        x, _, _ = model._standardize_user_data(
            x, check_steps=True, steps_name="steps", steps=steps
        )
        return predict_generator(
            model,
            x,
            steps=steps,
            batch_size=batch_size,
            verbose=verbose,
            workers=0,
            callbacks=callbacks,
        )
